A handheld cutting machine, which is constructed such that a user holds the machine by hand and performs cutting processing while moving the same along a cutting object, is configured such that a cutting machine main body is supported on an upper surface side of a base that is placed on the cutting object. The cutting machine main body includes a circular cutting blade that is rotated by an electric motor. The cutting blade is arranged such that a lower portion thereof is protruded from a lower surface side of the base to be cut into the cutting object. An upper portion of the cutting blade is covered by a main body case, and the lower portion protruded from the lower surface side of the base is covered by a movable cover. The movable cover is rotatably supported on the main body case, so as to be opened and closed depending on a cutting amount of the cutting blade into the cutting object, and is spring-biased to a closing direction.
This movable cover is positioned in the upper surface side of the base and is rotatably supported on an outer circumferential side of a cylindrical bearing box of the main body case. The bearing box has a bearing that rotatably supports a spindle to which the cutting blade is attached.
Cutting powder blown up from a cutting part by the cutting processing can be scattered into the main body case including surroundings of the bearing box. Conversely, in a rotatably supporting portion of the movable cover, formed between the movable cover and the bearing box is an appropriate clearance (gap) in a radial direction and an axial direction in order to secure smooth opening and closing operation of the movable cover. As a result, dust, such as the cutting powder can enter the clearance between the rotatably supporting portion of the movable cover and the bearing box. This may disturb a smooth opening and closing operation of the movable cover. Conventionally, a technique taught by, for example, a following Japanese Laid-Open Patent Application No. 2005-1896 is suggested as a dust-proof measure. In this conventional technique, a second bearing for supporting the movable cover is attached to the outer circumferential side of the bearing box apart from the bearing for supporting the spindle. The movable cover is rotatably supported via the second bearing, so that the clearance can be eliminated. In addition, a seal member of the second bearing is shielded by a seal cover, so as to perform dust-proofing.
However, in the conventional technique taught by the Patent Document described above, the second bearing is used in addition to the first bearing that rotatably supports the spindle on the main body case, so that the movable cover is rotatably supported on the bearing box. This may lead to increased costs. Therefore, it is desirable to provide a technique that is capable of reliably taking a dust-proof measure in the rotatably supporting portion of the movable cover without using such a special bearing. Thus, there is a need in the art to provide an improvised wheelchair seatbelt device.